Caster



A. M. BUDNICK ET AL CASTER Feb. 12, 1952 Original Filed July 6, 1948 INVENTORS' ABBA HAM M BZ/DN/CK NFL 5 0. BERG Reissued Feb. 12, 1952 CASTER Abraham M. Budnick andNels 0. Berg,

Seattle, Wash.

Original No. 2,505,852, dated May 2,1950,Serial No. 37,204, July fi, 1948. Application for reissue April 19', 1951, Serial No. 221,772

5 Claims. (01. 16-35) Matter enclosed in heavy brackets ['1 appears in the original-patent hut forms -no part 0! this reissue specification: matter printed in italics indicates the additions madelhy reissue.

This invention relates to casters, and particularly to casters for supporting and moving carts, tables, and various other mobile articles, or equipment, any of which we designate herein an article of furniture" [in straightlines]. As an example, such casters may beapplied to the bottom, of the legs, ,or similar framework, of a hospital cart, whereon a patient is moved, for example, from his .room to a surgery.

[In the use-of ordinary casters for such purposes lt is common to connect them to the bases or legs of such articles-leavin the supporting wheels free to swing or swivel circularly around the connecting point. With this construction the furniture or articles when pushed or pulled will not move in straight lines as the swinging 0f the wheels carries the articles in zig zag directions causing the article to collide or. strike against other articles of furniture or walls of the rooms frequently marring and injuring the same] Inany .such usage, it is often desirable to transport a load, such as a patient, and the cart whereon he rests, gently and smoothly over a considerable distance along a straightoorridor, yet. the cart must turn readily to enter or leave through a doorway and .to. negotiate turns in the corridor. Where the cart is thus to travel over some distance along a straight line, it is desirable th t the caster wheels be held against swiveling, and in particular against shimmy, and that they be held fixedly during .suchstraightline travel, in proper position. to accomplish such straight-line travel without effort on the part of the attendant who is pushing the cart, and'whose primaryconcern is the welfare of the patient. At .the same time, it is equally desirable that the cart be free to turn about. a corner so that, it may negotiate turns. through a doorway, onabouto corner in a corridor, so Iree in fact, thaithe attendant is not required manually, ,or by use of the foot, or otherwise, consciouslu to release a lock or other retaininameans ,such as holds the caster in ,the straighi-line position, but that such release becapable, of v accomplishmentuutomatically merely as a result .of the natural efiort, which such an attendant" makes in attempting to change, the course of such a cart, and to turn it about a bend, or deflect it from a straight-,liue. Moreover, when straightline travel isto be resumed, it is desirable that the caster automatically return .to, and secure itself in, this straight-uhead..-position, withoutconscious-efiort or. thought on the, part of ihc attendant a ar1o.us,.a t nts,.hav f snf m 1 P i vent suchflzig zag travel, particularly by brakes and forms of locks'which require the operator t0 ,,s t0 op or bend overto, connect the latches, and repeat such .movements to. free the latches or shift the same when the articles are to he moved in another direction] Accordingly it [It] is.[there for.e an] the primary object of this invention to, provide, in one complete assembly, a caster unit which may beattached for, use in the usual manner on the legs or bases of various articles .of furniture"? as ,hereinaboue defined, which require movement, fromplace to place, so constructed that when such article of furnie ture is [to be moved and, whereby, such articles when] pus hed or pulled straight ahead, the caster wheel willassume and be, rctainedautomat icalh "in properlocation for such straight ahead travel and which yet: will be self-releasing without conscious 'efiort on the part o ,f 'the attendant, when "the ntte ndant attempts to"turn the article ofjurniturc, or deflect it from straight-ahead traueL a n'd which, furthermore, will automatically mm; parts" to and "retain them in, straight ahead position when straightahead mou'eme'nt' is resumedafter a turnIb'y the operator will automatically travel in straight lines in the direction desired" by the operator].

'lnjpa'rt'icular, it {isde sired'to proyidefa caster unit of the general nature indicated," wherein, during normal operation,"th'ereis-iioneed for an attendantto release any" retaining" "means. manually, lby foo pedal, by'jstoop'ing, or "by any deliberate or mums act, nor isany such deliberateorcons cious act required to relocate and hold parts in straight-ahead position.

It is a further object to provide such acaster unit which may be applied to articles-of furniture of difleren't weight, length", or bulk, and which incorporates means which may be" ad'- y'usted once when the caster unit is installed, to pary the force required torjelease the locating means, in accordance with the weight,"length, or bulk of the particular article of furniture, and which, after the initial adjustment, ordinarily requires no further adjustment during the normal usage of'the' artic'leof jurniture and its easier unit, I I

[A particular object is to-provide a caster unit with all parts thereof connected together, and which: maybe :applied to any of the, articles desired to: be moved in straightlines and which may be alsoadapted for lateral travel] A particular object istoprovide a casterunit are connected ,together in in which all. parts,

3 use and which may be applied substantially as a unit to an "article of furniture," having [A further particular object is'to provide a caster with] a base'plate provided with one or more recesses, usually in its [on the] lower face, [thereof] and a locating ball resiliently supported beneath the plate for automatically seating in the recess, or recesses, when the caster wheel is in [alinement] alignment with the straightahead direction of travel desired for the furniture, the ball, however, being capable of being dislodged fromthe [recesses] recess by camming action initiated by a slight push sidewiseagainst the "article of furniture" [table, or articles to be moved, and], such as is the natural effort in purposely initiating turning, without stooping or bending over to manually move or adjust the ball or any control or actuator.

leg of an "article of furniture which is [anyarticle] to be moved; [.1 Figure 2 is a bottom plan view of the base plate, in the nature of a transverse section [taken] on line 2-2 of Figure 1, and Figure 3 is a fragmentary detail sectional [edge] view of the [cylinder and plate] locating means, taken on line 3-3 of Figure 1.

The need for a caster of the nature indicated above has been recognized heretofore and speciflcally as applied to a hospital bed or cart. It was considered necessary heretofore, however, to provide manually operable means to release the caster-locating element whenever it was desir'able to deviate from straight-ahead 'movement, and also in order to enable the casterlocating element to function to secure parts in the straight-line position, when desired. If the advantages of the locatin means to secure the casters for straight-ahead movement were to be realized, it, was nwessary to remember to reach down and manually release the positive locking or locating means as each turn, whether large or slight, was approached, and then to reach down again and restore the same means to operative condition after resuming straight-ahead travel. Alternatively it has been proposed to accomplish similar results by foot pedals, or by stooping down to gain access to the casters themselves, and their locking or actuating mechanism. It followed that such devices in actual use would constitute so much of a nuisance that they would be but seldom operated in the fixedly located straight-ahead position, but would normally be left unsecured and free to swivel at all times through 360. All the advantage of the casterflxing means would be lost by reason of the necessity for repeated, conscious, and awkward adiustments.

By means of the present invention, in the use of which there is no necessity to give conscious thought to the securement or release of the easier wheel from its straight-ahead position, or its return thereto, nor to perform any act related to the same, the normal forces engendered by an attendant in moving the "article of furniture" about a turn, will effect release of the locating means, and the same will automatically return 4 to secured position for straight-ahead travel upon resumption of such straight-ahead movement.

[Like characters on the different figures represent like'part's'. Numeral 5 indicates a plate of suitable size for attachment to the bases of articles to be moved such as leg A for a cart or table, by means of screws through holes 6 or by a vertical pin 1 either singly or together. A spindle or bolt 8 preferably integral with the plate or affixed thereto is extended vertically downward from the center thereof. On the spindle is rotatably mounted a tubular yoke or casing 9 having a pair of jaws l0l0 laterally extending therefrom and 'afiixed thereto and preferably integral with the yoke. The outer ends of the jaws carry an axle II on which is rotatably mounted 'aWheel'IL].

[To facilitate swivelling movement of the yoke on the spindle suitable sets of balls indicated as l3 and I4 disposed in ordinary races as I3 and I4 are provided in the casing 9, at the top and bottom of a central core I5. The upper balls bearing against the bottom of the plate and the lower balls and race gsupported on the bottom of the casing It. An adjusting nut l1 threaded on the lower end of the bolt or spindle maintains the yoke in suitable relation with the plate for operation in various relations or. positions beneath the object to be moved and for supporting such object or article in various positions] [In order to latch or connect the yoke and plate so that the wheels will carry the article in straight lines andto prevent zlg zag movements of the articlesuch as a cart, table and the like we have invented means for automatically latching the plate to the yoke when the jaws are extended with the wheels in the line or direction of travel desired for the article. For this purpose a cylinder I8 is vertically attached or integrally formed on the rear portion of the casing opposite to the jaws and wheels. The cylinder is open at the top adjacent to the lower face of the plate and a ball I9 is freely disposed in such open top of the cylinder and normally pressed upward against the plate as by a helical spring 20. The spring is preferably supported on a washer 2| pivotally connected on the top of an adjusting screw 22 for regulating the pressure of the spring against the ball from the.

bottom thereof and the pressure of the top of the ball against the plate. r The screw is threaded through a web 23 in a sleeve 24 which latter is threaded at the flange 25 by threads 26 to the lower walls of a cylinder. The lower flanges of the sleeve provide a guard for the lower portion of the screw, which is provided with notch 21 for adjustments as by a screw driver] 7 [The lower face of the plate near the outer edge thereof is provided with a pair of recesses as 28 and 29 in alinement with the orbit of the ball when moving around upon the spindle. These recesses are preferably formed oppositely from each other but in alinement with the cart or article to be moved longitudinally therewith. Thus when the wheelsand jaws are in alinement with the direction of travel desired the ball will be in juxtaposition with one of the recesses, and will be compressed into such recesses with suflicient force by the spring to prevent removal thereof by any normal lateral disposition of the article to be moved, and when such article is pushed 'or pulled longitudinally by the tudinally as desired. The pressure of the spring,

76 however, is so adjusted that while it will norcacao nnmuy malntaln lthe ballln such recess yet the operator-may readily-dislodge" the same' by a. relatively slight pressure on either side of the -"tab1e-,- -eart orbther=artic1e to be moved whereupn the ball will roll freely on the lower face (at the plate, and the article may be' moved lat- "-er'ally 'as up against a wall as' 'may ibe desired by the-opet'a'tor. *It will be und'ersto'od' 'that by the u'se-of the oppositelrdisposed recesses-the caster wheelsmay be operatedin straight lines either forwardly "from or trailing behind i the point orpo'sition' otattachmeht of the plate to the 1 said article tobe mov'ed." The e'dges of the recesses-are preferably rounded-to a curve to *eonrorm "with the surface ofth'e b'all'to facilitate the entry and removal of -the*b'a 11 *to' or from the "-reces'ses] The lower portion of the leg-=Aof an article of furniture, which is to be mounted on such casters, is fltted to receive the base or swiveldefining unit ofthe "casten'whi'ch, in the form shownin' 'the presentillustration, constitutes a horizontal "plate- 5 where'on is-- centrally secured a spindle of-which the upperpart 7 enters a bore ail-eased upwardly from the bottomof the leg l Apand the lower-portionof pintle" 8 projects vertically and centrally below the plate 5, to denae the-swivel axis S. "The plate may b o-secured immovably to-the leg by means such as the screws 6.

'fA 'yokegenerally indicated bg'the numeral 9 "is formedat its upper-end with means complemental to*t-heswivel-defining means of the "mounting plate 5,-and at its lower end is formed with furcations 10, directedlaterally from-the end of 'the' piritle 8' prevents accidental disassembly ofsthe swivel-mount, and holds the yoke 9 as a whole upon the fixed mounting member.

The'yoke at its upper portion is formed with a boredefined,-in -the-particular form illus- *trated .--by the cylinder- 18- which is-generall 1/' "parallel tobut ofiset radially-fromthe swivel axis 8* by a distance D2. This bore in use is open only at its upper end, within--which is mounteda-ball 19 or similar-locatingmember.

A compression spring-20 received within the -'lower part of the boreor cylinder 18 urges'the "ball *19 upwardly against the-bottom=*of the plate 5, and in doing so, reacts from a washer 21, which is swivelled upon the reduced upper end of an adjusting screw 22, threaded within the central web 23 of a cap or sleeve 24, which in turn is threaded at 25 upon the projecting lower,end of the cylinder 18. By engagement of a screw driver in a transverse slot 27 in the lower end of the adjusting screw 22, the force of the spring 20 may be varied at will, for a purpose which will shortly appear. The depending skirt of the cap 24, below the web 23, protects the lower end of the adjusting screw from accidental injury. In the lower face of the plate 5, at a radial distance D2 to register with the ball 19 or similar locating means, are formed depressions 28 and .29. It is preferred that these or the complemental locating means 19 (or both) be rounded, at least in the cirone -another,.and .-"-that .-the c'asterwaunit be mounted in such relation to 'the leg;A--oj-:the

' longitudinal sense.

-articleof 'furniture, that) the complemental locating means 19 and 28 or 29 will be in engagement when the'caster wheel'12 is'lo'cated in such plane as-will causestraight-ahead movement of the "article of vfurniture:in either There could be more than two such recesses, if desired, located otherthan "diametrically opposite, or one would suffice, al-

though two are preferred where the articleof furniture is to be moved first in one senseflznd then in the opposite sense, and straight-ahead fixation of -the caster wheels isldesiredin; either such sense.

Assuming" that the caster wheel has'swivelled so' that the retaining ballr19 is out of engagement with either ofrtherecesses 28 and 29, when the attendant pushes the carton other article'of furniture in a straight-ahead direction-the contact point C of'the wheel.12 with the floor F will cause that wheel to 'trail,uand toIassume the correct straight-ahead position, andthereupon the ball' 19 will drop automatically into one or the other of the recesses 28'and 29 under 'the urging of the spring '20, and so long as the=force applied to the cart is generally straight ahead,

there is no force, other-than such as wouldtend to cause the wheel to:shimmy:,"which acts to'dislodge the ball 19 from its recess, and the-retaining means are designed to prevent shimmy, so

"that the caster wheel is maintained in its proper straight-ahead position,-and shimmy thereof is prevented. However, when it is desired to turn a corner, the attendant will naturallylpush'rthe rear-end, oripull thefbrward end, laterally of its previousstraight-ahead' path. This lateral -force is applied to the-cart itself, and sincethe leg'A is an integralspart of the c'art or similar article of furnit'ure, a lateral force, isap'plied-to 'ith leg. A, and thisacts upon theicaster unit: by

transferring that lateral force to the spindle portion at 7. *Now it will be observed that the point of contact 0 of the wheel withthe'flooris at a -given-moment arm D1 about the :swivel axis S,

defined by the spindles "two'portions, 7 and 8. Consequently, the lateral force'applied to the pintle 8 tends'to rotate the pin'tle and-the mounting-portion-of the caster unit about-the point of contact C of the caster wheel IZ'with the floor. Preferably, but not necessarily, this moment arm D1 is in excess of'the'radial distance D2 of the ball 19 from the swivel axis S, and having thus a definite and predetermined mechanical advantage, the lateral force thus applied acts to dislodge the ball 19 from its recess 28 or 29, and to press the ball 19 inwardly within its bore 18, in opposition to the spring 20. The force of the spring is calculated to be just sufficient that a ciently that,*as applied to the particular article, and as thus initially adjusted in force, the normal lateral pressure on the "article of furniture, acting to swing it about its distant end,

where it rests upon the floor, will release the retaining ball, or equivalent retaining member. Thus one caster assembly is suited, by proper adjustment, for application to articles of furniture of various lengths, weights, bulk, or other characteristics. Such adjustment is an initial one only, and ordinarily no subsequent adjustment is required, unless by material change of weight,'length, or the like, the force required to dislodge the retaining element 19 from. its complemental recess 28 or 29 is appreciably altered.

[Having described our invention we claim as new for patent We claim as our invention:

1. A caster unit including a plate adapted to be secured to the extremity of a piece of furniture, a bolt integral with and depending from said plate, a cylinder carried by said bolt and adapted to rotate about said bolt, a yoke depending at approximately an angle of 45 from said cylinder and supporting a caster wheel, a second cylinder secured to said first mentioned cylinder, a spring pressed ball carried by said second cylinder and engaging the underside of said plate, said plate being formed with. depressions diametrically on opposite sides of said bolt to re ceive said ball, and means for varying the force with which said spring pressed ball is forced against [the] said plate whereby the first cylinder may be rotated about the bolt to bring the spring pressed ball into either one of the alined depressions.

2. A caster unit including a plate adapted to be secured to a piece of furniture, pivot means defining an axis fixed relative to said plate, disposed beneath and carried by said plate, a member disposed beneath said plate and rotatable about the fixed axis of said pivot means, a yoke depending from said member and extending laterally from the pivots axis, a caster'wheel supported by said yoke with its axis disposed eccentrically of said pivots axis, and a spring-pressed detent carried by said member eccentrically of the pivo-ts axis and engaging the underside of said plate, said plate having a socket similarly located eccentrically of the pivots axis to receive said detent for locating and holding said yoke against involuntary swiveling relative to said plate.

3. The caster unit defined in claim .2, in which the spring-pressed detent includes a detent ball, a helical spring, housing means defining a bore receiving said spring and holding said ball in position pressed by said spring, and spring tension adjusting means carried by said housin means, engageable with said spring and movable to alter the force of said spring exerted on said ball. 1 a

4. A caster unit including a Plate adapted to be secured to a piece of furniture, a pivot defining an axis fixed relative to said plate, carried by and depending from said plate, a cylinder carried by said pivot and rotatable about the fixed axis thereof, a yoke depending from said cylinder and extending laterally from the pivots axis, a caster wheel supported by said yoke with its axis disposed eccentrically of said pivots axis, and a spring-pressed detent carried by said cylinder eccentrically of the pivots axis and engaging the underside of said plate, said plate having a socket similarly located eccentrically of the pivots axis to receive said detent for locating and holding said yoke against involuntary swiveling relative to said plate.

5. A caster unit including a plate adapted to be secured to a piece of furniture, a pivot integral with and depending from said plate and defining an axis fixed relative to said plate, a cylinder carried by said pivot and rotatable about the fixed axis thereof, a yoke depending from said cylinder and extending lateraly from the pivots axis, a caster wheel supported by said yoke with its axis disposed eccentrically of said pivots axis, a second cylinder secured to said first-mentioned cylinder eccentrically of the pivots axis, a springpressed ball carried by said second cylinder and engaging the underside of said plate, said plate having depressions disposed diametrically on opposite sides of said pivot and located eccentrically of the pivots axis corresponding to the eccentricity of said second cylinder, to receive said ball, and means for varying the force with which said spring-pressed ball is forced against said plate. I

ABRAHAM M. BUDNICK. NELS O. BERG.

REFERENCES CITED The following references are of record in the file of this patent or the original patent:

UNITED STATES PATENTS Number Name Date 1,752,183 Kell Mar. 25, 1930 1,827,595 MacGuire Oct. 13,- 1931 1,896,234 Hathorn Feb. 7, 1933 1,958,494 Pehrsson May 15, 1934 2,051,627 Weinmann Aug. 18, 1936 2,306,179 Mulholland Dec. 22, 1942 2,425,246 Kalvin Aug. 5, 1947 2,480,524 Vallone et a1 Aug. 30, 1949 2,525,362 Levy Oct. 10, 1950 

